Electrothermal modeling tool



May 16, 1933. c. MacH, LINDSAY 1,909,774

LECTROTHERMAL MODELING TOOL Filed July 1 5, 1929 INVENTOR.

ATORNE'YJ 10 be understood that Wit l5 stated 5 different shapes and sizes readily changed I Patented" May p 16 1933 UNITED STATES PATENT `'o1-"FICE CHARLES MACHENRY LINDSAY, or Tiwy, NEW Yom:

` nLEcfrnorHnnmL MODELING 'rooL Application led July 15,

This invention relates to electro-thermal modeling tools for modeling or shaping plastic materials such as wax, and like materials used in making dentures, costume manne 5 quins, Sculptured rigures'and the like, whose plasticity is dependent upon the application of heat or heated tools.- While the inventionv 20 a device of this character Which may he easily and conveniently handled, Y and which will maintain a desirable and useful temperature, and which will permit the ready 'interchange of tools for Work ot-diderent character, While 25 permitting the same to be conveniently operated without burning the operatorls hand or overheating the Work upon which .it 1s A employed, llhe result has heen that even the largest dental laboratories still use the un- .39 necessarily impractical method of heating the tip of a spatula in the dame ot a Bunsen hurner, then applying it to the Wan, and re heating and again applying9 which practice is exceedingly time consuming and laborious. The present invention is therefore directed primarily to a small, compact and light tool which overcomes the disadvantages incidentto known devices of this character, and which may be easily and conveniently maintained at desired temperatures whereby the Working of the' wax or other plastic material may he rapidly and expeditiously carried forward.

' A further ohject is-t'o provide a sate and foolproof device of the above character,

l" which will be unlikely to burn out or cause injuryor damage if the operator fails to turn orf the current.

" Y WA further object is to provide a device oit the above character with working tips of 1929. Serial N0. 378,502.

and securely clamped or released without burning the operators lingers.,

A further object is to provide a means of connecting the improved modeling tool to the lighting service in such a manner that 55 the flexible cord or Wire will not twist or when turning the tool in use, such being accomplished by the provision of an improved swivel connection between the ductor.

A further object is to provideI a modeling tool With a means for controlling the temperature thereof, havingy a, sucient range of temperature to permit a rapid melting or `flowing of the material when blocking out Work and a lower temperature :for the line inishing touches.

@ther objects will he in part ohvious trom the annexed drawing and in art herein after indicated in connection t erevvith the following analysis of this inventiona This invention accordingly consists in .he

features of construction, combination parts and in the unique relation of the nu n hers and in the relative proportioning Ad disposition thereof, all as more completely outlined herein.

To enahle others skilled in the art to comprehend the underlying features ther or; they may emhody the same by the numer, :is merlin-cations in structure and relation conu templated hy this invention drawing dep tm ing a preferred ,torni of th e invention been annexed as a part ot this disclosure, in S hig. l is perspective view ot the complete apparatus connected and' ready for use;

Fig. '2 is enlarged detail vieri showhng the Wiring ldiagram;

l*1 ig. 3 is 'an approximately full size longia tudina-l, sectional vieri oit the complete do vice; l

Fig. is an enlarged detail sectional vier? of the connection between the electro-thermal tool and the exihle cord from a .source or electrical supply, hnovvn as 66jack type cord connector.;

Fig. 5 illustrates in perspective two forms ot interchangeable tools.

Referring now to the drawing in detail'-w tool and conand more particularly to Fig. 1, indicates a plug adapted to be tapped into any electrical socket, which is connected by means of a twin conductor 6, one conductor of which is in series, with any standard form of rheostat 7. The lrheostat is provided with a control handle 8 and terminals 10, to which flexible twin conductor tinsel wire 11 is connected to a jack type connectorv12 shown in detail, Fig. 4. This jack type connector is of the swivel type as will be hereinafter explained and adapted to receive a plug 13 at the end of the working tool as shown in Fig. 3.

Referring to Fig. 3 in detail, it will be noted that the body portion of the spatula comprises an insulating barrel or casing 14, of material such as bakelite, and preferably not over three-eighths of an inch in outer diameter. A base or core 40, to be hereinafterr described, extends thru the casing 14, and is threaded at its plug end. Disposed to abut the ends of the casing 14 and slidable axially on the base 40 is a cup washer 15, which is engaged by a knurled nut 16 running on the threaded portion of the base 40. The said base is axially bored at its other end to receive a block 42 threaded therein and locked against rotation by a pin 43. The said block terminates beyond the casing 14,

and being 'of a smaller diameter than the base 40, there is formed a narrow annular chamber between the outer surface of the block and the inner diameter of the sleeve 14.

Forwardly of the block 42 and in abutting engagement therewith, extend the chuck jaws 17 with their usual' spindle portions, each having at -their forward end the inclined beveled surfaces 17a, which coact with the correspondingly coned surface 18a of an annular member or collet 18. A sleeve 19, preferably of aluminum, is disposed about the collet member 18 and engages, atione end, the outer incline surfaces 18a thereof. Disposed between the sleeves 14 and 19, there is provided an irregular or triangular guard formed of asbestos pad 23 protected on bot-h sides by sheets of insulating material 24. The tools or tips generally illustrated in Fig. 5 each comprise a working tip 20, a collar portion 21 and a shank portion 22. They are preferably made of metal having the desired hardness and heat conductivity, and the shank portion 22 is engaged by the chuck jaw 17 and held tightly therein, as follows. As the nut 16 is turned on the base 40, it causes axial movement of the collar 15 which is imparted to the sleeve 14. The guard 23, 24, being substantially rigid, transmits this movement to.l the sleeve 19, which, by reason of its engagement with the inclined surface 18a of collet member 18, imparts aslight axial travel to the collet 18, which thru the wedging action of the inclined portion 17a causes the jaws 17 to be securely clamped on the shank 22 of the tool.

Wound about the chuck spindle portions and preferably insulated therefrom is a plurality of turns of very fine resistance wire which forms a heating coil 50, the ends of which coil are connected with terminals as will be shortly explained. It may be assumed that when the current is turned on, this coil -becomes heated to a medium degree of ternperature, the desired degree of which may be controlled by the rheostat 7, the main point being that the temperature is not excessive, but is sufficient to heat the chuck and transmit such .heat to the shank 22 of the tip, from which heat is conducted to the tip 20 thereby permitting the wax upon which the spatula is generali used to be molded and shaped as desire It will be noted that the heating extends beyond the end of the casmg 14a relatively short dista-nce, and in practice only about one inch or. less, and at the end of this heated portion, the guard 23, 24 is disposed, and immediately adjacent the guard is provided a finger grip such as a tapered or cylindrical cork body 25. The triangularguard not only protects the fingers of the operator from radiated heat from the coil, but if the device is resting upon a table, the irregular configuration, that is, triangular or square, prevents the spatula from rolling should the table be slightly inclined. The cork grip 25 isv preferable over other materials, inasmuch as it absorbs moisture and perspiration from the finger tips, provides a firm, non-slipping grip, andV is more or less heat insulating. An insulating sheath 51 is preferably arranged between the sleeve 19 and the coil, extends thru the guard 23, 24, and terminates in the space formed between the sleeve 14 and the plug 42 in the form of an asbestos cord winding 51a. The plug 42 may be formed with breathing holes 44 disposed in normal relation as indicated.

Referring to Fig. 4, it will be noted that the jack type connector assembly consists of a metal base 26 cut away longitudinally coil 20- on one side as indicated by the line 27. This l base serves as one side of the line and is connected to wire 28. A spring contact arm 32 is mounted on, but electrically insulated as at 31 from the connector base 26 and held firmly in position by the screws 30. Part of one end of the base 26 is left cylindrical, threaded on the outside and slotted on the end so that a Screw driver may be used .to screw it into the insulating sleeve 12 which is threaded to receive it. Thus, when the plug end 13 of the spatula shown in Fig. 2 is inserted, the electrical circuit is complete. This plug end assembly 13 comprises an outer knob 33 having a central core34 connected with one terminal 35, while connected with the other terminal 37 about this core and in-` ing. Most of the failures of socket appliances result from failure to provide means in the connections used in conventional. designs to relieve the twistingor kinking strains on the conductor'.

The plug 13 and connectors 35, 37 herein shown are primarily the Wiring elements and are assembled on the base 40 of insulating material and held in place by means of set screws/.1.1. After the wiring portion is assembled, a set screw 42a passes thru the sleeve 14 into the base 40, thus maintaining these parts in operative relation. Itis obvious that a base having the Wires molded thereon may be substituted. Likewise, the base 40 and sleeve 14 may be formed hexagonal or of other irregular configuration to prevent'turning therebetween.

As herein shown, the .rheostat is provided as a separate element independent of the dental spatula. This is primarily because the eXtra weight by mounting the rheostat directly onv the spatula would soon tire the wrist and fingers of the operator, thus diminishing the effectiveness of his work, and for this 'reason it is preferably to mount the same separately and contact it with the spatula by Ya very light flexible cord having fa swivel connection as shown. Suilicicnt electrical resistance is inherent to the selfcantain'ed Winding permitting it to withstand full line voltage, in the event of the rheostat becoming short-circuited. l

From theA above, it Will be seen that the present invention comprehends a simple and l practical device of the above character particularly adapted for dental use. The device is of about the size and weight of the average fountain-pen'or less, and may be used indefinitely without tiring the operator. When its use is started, the current is lpreferably turned on full thru the rheostat 7, and as soon as the desired temperature is reached, the current is reduced in order to maintain the temperature ofthe tool 20 at just the right degree so as topermit eflicient operation upon the wax, yet without danger of causing puddling of the wax. VThe cork grip 25 enables the operator to conveniently move the spatulain any directionnmd withoutl danger of the tool .slipping from 'his fingers due to perspiration, for example. The guard 23, however, will protect the lingers to a large extent from heat radiations. The swivel connection 13 permits the electrothermal dental spatula to be turned and revolved in any direction without kinking the cord 11. The collar 21 prevents the melted lastic from ruiming into the chuck and forth from the wax to the Bunsen burner as' heretofore.

Without further analysis the foregoing will so fully reveal the gist of this invention that others can by applying current knowledge readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and therefore such adaptations Should and are intended to be comprehended Within the meaning and range of'equivalency of the following claims.

l claim:

1. An electro-thermal modeling tool comprising a barrel of insulating material, a working tip, electrically operated tip holding means.l disposed near one end of the barrel for heating the tip'and actuable to hold the same in working relation, means disposed adjacent the other end of the barrel for actuating the holding means, and a plu' extending beyond said last-named end o the barrel providing a swivel connection with'a source of current. v

2. An electro-thermal modeling tool comprising a barrel portion of insulating material, a chuck at the end of said portion, a coil surrounding said chuck, means for releasing the chuck, and areleasable tip having a shank adapted to be engaged by the chuck and heated by said coil.

3. An electro-thermal modeling tool comprising a barrel portion of insulating material, a chuck at the end of said portion, a coil surrounding said chuck, means near ,the opposite end of the barrel portion for releasing the chuck, and a releasable tip having a shank adapted to be engaged by the chuck and heated by said coil. 1 v l 4. An electro-thermal vmodeling tool comprising a barrel portion of insulating mate-- rial, a chuck at the end of said portion, a coil surrounding said chuck, means near the opposite end of the barrel portion for releas- ICO il? the chuck, a releasable tip having a shank a apted to be engaged by the chuck and heated by said coil, and a plug adjacent said chuck release and providing a swivel connection Y 8. SOllICe f Current. f v

5. In a tool of the character described, the combination of abody portion, a working point having a tip and a shank, a chuck disposed at one end of said body portion and aving spindle and jaw portions, anelectrically operated heating coil wound on the spindle portion, and a member threadedly A engaged with the other end ofthe body portion or opening and closing the chuck jaws.

6. An electro-thermal modeling tool comprising a body portion having a hollowed recess at one end containing movable chuck jaws, an electrical heating coil surrounding said chuck jaws, a member for opening and to 1provide a swivel connection with any suitab e source of electrical current, and a tip having a shank adapted to be'engaged by said chuck jaws. l

8. An electro-thermal modeling tool comprising a body portion having a hollowed recess at one end containing movable chuck jaws, an electrical `heating coil surrounding said chuck jaws, a member for opening an closing the chuck jaws, a plug adapted to provide a swivel connection with any suitable source of current, a tip having a shank adapted to be engaged by saidchuck jaws, an insulating housing enclosing said parts between the tip and plug, a finger grip surrounding said housing, and a heat insulating'guard adjacent the finger grip.

9. In a modeling tool of the character` described, the combination of a body portion including a barrel of insulating material and a sleeve at one end thereof, a worln'ng point having a tip and a shank, a chuck operatively arranged in the sleeve and comprising spindle and jaw portions and a collet member, the said sleeve being operative, upon slight axial movement, to engage the collet member whereby to actuatethe chuckfjaws into gripping or non-gripping relation relative to said shank, an electrically operated heating coil wound on said chuck spindle, and means to impart a slight axial movement to the sleeve,

whereby to actuate the chuck jaws.

10. In a modeling tool of the character described, the combination of a .body portion l including a barrel of insulating material and a sleeve at one end thereof, a working point having a ti and a shank, a chuck operative-l ly arrangeld in theY sleeve and comprising spindle andl jaw portions and a collet inember, the said sleeve being operative, upon slight axial movement, to en age the collet member whereby to actuate t e chuck jaws into gripping or non-grippin relation relative to said shank, an electrically o erated heating coil wound on said chuck spin le, and means inclusive of said barrel to impart a slight axial movement to the sleeve, whereby to actuate the chuck jaws.

11. In a modeling tool of the character described, the combination of a body portion including a barrel of insulating material and a sleeve at one end thereof, a working point having a tip and a shank, a chuck operatively arranged in the sleeve and comprising spindle and jaw portions and a colletl member, the

said sleeve being operative, upon slight axial movement, to engage the collet vmember whereby to actuate the chuck jaws into gri ping or non-gripping relation relative "to said shank, an electr1cally operated heating coil wound on said chuck spindle, and a member threadedly engaged with said body portion near the other end of the barrel operative to impart a slight axial movement to the sleeve, whereby to actuate the chuck jaws.

12. In a modeling tool of\the character de scribed', the combination of a body portion comprising yan insulating holding barrel and asleeve disposed in axial jalignment therewith, a working point having a shank, means operatively disposed in the sleeve to hold the point in working relation, a heating-coil arranged in the sleeve and surrounding the shank for heating the holding means and the working point, and a heat protective ard disposed between the barrel and s eeve, whereby to protect the fingers of the operator from heat engendered by said coil.

13. In al modeling tool of the character described, the combination4 of a body portion comprising aninsulating holding barrel and a sleeve disposed in axial alignment therewith', a working point 'having a shank, means operatively disposed in the sleeve. to `hold the point in working relation. a heating coil arranged in the sleeve and surrounding the Vshank for heating the holding means and the working point, a heat protective guard disposed between the-sleeve and barrel, and a finger grip disposed adjacent said guard and about said barrel, said guard and grip being operative to protect the fingers of the operator from heat engendered by said coil.

14. In a modelingvtool of the character de-l scribed, a body portion comprising a holding barrel and a sleeve disposed in axial alignment therewith, an electrically heated chuck operatively-mounted in said sleeve, a working point having a shank adapted to be gripped by said chuck, said chuck bein releasable upon slight axial `movement o the sleeve whereby to release the shank, and means remote from said sleeve actuable to imparta sli ht axial movement thereto.

I igned. at Washington, District ofColumbia, this third day of J u1 1929.

CHARLES MACHE Y LINDSAY. 

